The invention relates to a coating device, in particular for painting motor vehicle bodies, and to a corresponding operating method in accordance with the preamble to the sub-claims.
In modern painting systems for the mass painting of motor vehicle bodies, painting is usually by means of atomisers (e.g. high-speed rotary atomisers) with only one paint inlet, which are therefore connected to a separate colour changer on the inlet side, so that one single atomiser can apply paint in different colours. The entire train of pipes between the colour changer and the atomiser must be flushed out when the colour is changed, to clear paint residue from the train of pipes. Firstly, this causes colour change losses in the range of 25-70 ml (depending upon the embodiment), which may even exceed 100 ml in exceptional cases, and, secondly, the time required for a colour change, in the range of 8-20 seconds is an irritation, although times of 13-15 seconds are usually achieved. The necessary colour change time depends on the flushability of the paints used, the flushing agent used, the pressure of the media, the structure of the paint-handling components and the position of the components in the application device.
Atomisers with an integrated colour changer (ICC) are also known, for example from EP 1 502 658 AI. The advantage of such known atomisers with an integrated colour changer is the low volume of the train of pipes between the integrated colour changer and the application element (e.g. a bell plate), which advantageously entails lower colour change losses and a short colour change time. However, the fact that the possible number of colours is limited, because the space available for installation in the atomiser is re-striated, is a disadvantage of known atomisers with an integrated colour changer.
Different painting systems, variously having an internal or external colour changer, are known from DE 697 22 155 T2, DE 696 22 407 T2, DE 103 42 643 A1, EP 1 502 658 A1, DE 101 57 966 A1, WO 2006/004601 A1, DE 103 35 358 A1, Dr. Richard Laible: “Umweltfreundliche Lackiersysteme für die industrielle Lackierung” [Environmentally-friendly painting systems for industrial painting], 1989, expert Verlag, Ehningen, p. 55; Joachim Domnick: “Oversprayarme Spritzlackiertechnik” [Low-overspray paint spraying systems], Metalloberfläche [Metal Surfaces] January 1997, pp. 43-45, DE 10 2004 038 017 A1, DE 10 2004 033 619 A1 and DE 36 41 416 A1. However, the external colour changer only has one paint outlet and is not configured as an A/B colour changer. If feeding low runners through the external colour changer, the problem therefore arises that a relatively long colour change time is required when changing from one low runner to another.